title: Light-induced variations of retinal sensitivity in rats.
abstract: OBJECTIVE
  ERG responses were measured as a function of Ganzfeld luminance to evaluate functional damage induced by light on rat retinas.
  
  
  METHODS
  Wistar rats were exposed to a fluorescent light of 1700 lux for 12 h, 24 h, 48 h and 72 h. We recorded ERGs before and one night after exposure, then 3, 8, 15, 22 and 29 days later. The b- and PIII-wave amplitudes were plotted against luminance for each group at each recovery time.
  
  
  RESULTS
  The retinal damage induced by a pupillary illuminance of 1700 lux ranged from low to severe as exposure duration increased from 12 h to 72 h, respectively. We observed an effect immediately after light exposure but no improvement during the recovery period. The b-wave amplitude was reduced by 40, 60, 80 and 90 percent after 12, 24, 48 and 72 h of light exposure, respectively; the PIII-wave amplitude was reduced by 30, 40, 70 and 90 percent after these respective exposures. The Ganzfeld luminance eliciting a 50 microV b-wave amplitude increased significantly with exposure duration, but the luminance eliciting the maximal b-wave amplitude was not dependent on this duration. Hence we suggest that the ERG decrease is due to a reduction in photoreceptor number.
  
  
  CONCLUSIONS
  We present a full analysis of the electrophysiological parameters recorded from light-exposed or non-exposed rats. This model is a useful tool to study in vivo retinal degeneration.
authors.affiliation: Laboratory of Biophysics, School of Pharmacy, University of Auvergne, Clermont-Ferrand, France. isabelle.ranchon@u-clermont1.fr
authors.forename: I
authors.initials: I
authors.lastname: Ranchon
authors.forename: J M
authors.initials: JM
authors.lastname: Gorrand
authors.forename: J
authors.initials: J
authors.lastname: Cluzel
authors.forename: J C
authors.initials: JC
authors.lastname: Vennat
authors.forename: M
authors.initials: M
authors.lastname: Doly
mesh_terms: D000818:Animals; D004596:Electroretinography; D008027:Light / Q000009:adverse effects*; D008297:Male; D011833:Radiation Injuries, Experimental / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D012160:Retina / Q000473:pathology / Q000503:physiopathology / Q000528:radiation effects*; D012162:Retinal Degeneration / Q000209:etiology / Q000473:pathology / Q000503:physiopathology*; D012684:Sensory Thresholds